1. Field of the Invention
The present invention relates to a receiving apparatus having an adaptive array antenna and relates to an array combing method.
2. Description of the Related Art
The following will explain a convention receiving apparatus. FIG. 1 is a primary block diagram showing a schematic configuration of the conventional receiving apparatus. In the explanation set forth below, it is assumed that the number of branches is two.
In FIG. 1, antenna elements 11-1 and 11-2 are provided on a branch-by-branch basis to receive radio signals. Reception processing selections 12-1 and 12-2 are provided on a branch-by-branch basis to perform reception processing with respect to received signals. A timing control selection 13 acquires symbol synch timing to perform control of synch timing in the apparatus. A demodulation processing section 14 performs training processing and tracking processing with respect ti the output signals of reception processing sections 12-1 and 12-2.
A configuration of demodulation processing section 14 will be explained with reference to FIG. 2. FIG. 2 is a primary block diagram showing a schematic configuration of demodulation, processing section 14 of the conventional receiving apparatus.
In FIG. 2, FFFs (Feed Forward Filter) 21-1 and 21-2 are provided on a branch-branch basis to absorb timing jitter and synch shift. A tap coefficient estimating section 22 estimates tap coefficients of FFFs 21-1 and 21-2 based on a result of equalization processing made by a Viterbi equalizer 24 to be described later.
A combing device 23 combines the received signals of the respective branches output from FFF 21. The Viterbi equalizer 24 provides equalization processing with a Viterbi algorithm to the received signals combined by the combing device 23 based on the symbol synch timing acquired by the timing control section 13. Since this equalization processing is already known, the specific explanation will be omitted.
Thus, the conventional receiving apparatus passes the received signal through FFF every branch in the first part of array combine processing to update the tap coefficient of the FFF adaptively, thereby absorbing timing jitter and synch shift.
However, the conventional receiving apparatus has FFF every branch, and this causes a problem in which the amount of operations is increased so that much converging time for tap coefficient is required.
It is an object of the present invention to provide a receiving apparatus in which the amount of operations is small and converging time for tap coefficient is short, and to provided, the array combing method.
The present invention calculates a weighting factor from a tap coefficient estimated by training processing, assigns weights to the received signals of the respective branches using the calculated weighting factor to combine these signals, and passes the combined signal through FFF, whereby achieving the above object.